Estimating Trends and Return Periods of Daily Extreme Precipitation Associated with Tropical Cyclones in the Core North American Monsoon

Abstract

The largest number of tropical cyclones (TCs) is generated in the northeastern Pacific Basin. These storms can produce extreme precipitation (EP) in northwestern Mexico, causing loss of life and environmental damage. It is important to understand the dynamics that cause the EP associated with TCs, since most human activity requires planning to adjust to the dynamics of local climate changes. Therefore, in this work the goal was to estimate the trends and return periods of the average annual daily extreme precipitation (AADEP; 95th percentile, P95) in the June-September season in the core North American monsoon. To do this, daily precipitation data from 1961 to 2000 from 48 climate computing (CLICOM) weather stations located in the core of the North American monsoon were used to determine AADEP:1. Non-parametric trends with Mann-Kendall tests and Sen's slope estimator. 2. Linear trends of annual averages of 95 (P95) and 99 (P99) percentiles with the least squares method. 3. Return periods with the Gumbel frequency distribution function. The results disclose a significant upward trend in the intensity of P95 increases in mountain stations, which may be related to a greater contribution of precipitation associated with TCs. The seasonal contribution of P95 in coastal stations and the total monsoon precipitation did not show statistical significance at α = 0.05. The return periods of P95 associated and not associated with TC's from 2005 to 2500 were calculated. Return periods of P99 have been rising since 2010 and will continue to 2500. For P95 events associated with TCs, the anomalies are expressed with synoptic conditions of simultaneous positive anomalies in the Pacific Decadal Oscillation (+PDO), negative anomalies in the

Seasonal Trend Indicators and Return Periods of Meteorological Drought in the Northern States of Mexico

“…The few ST of Prec may be associated with tropical cyclones. The core North American monsoon region, constituted by SIN, SON, and CHIH, is vulnerable to the effect of ST in Prec associated with tropical cyclones [18]. The excess rainfall associated with these events can severely affect soil in the form of water erosion and disaggregation by torrential rains [49].…”

“…A positive value of Z std indicated a PT and a negative value indicated an NT in the data [34]. The magnitude of each trend was estimated using Sen's slope estimator [18] from among the possible slopes that can be calculated for a time series [31,35]. …”

“…However, the IDW has the disadvantage that it tends to generate closed surfaces around the data when the power coefficient (P) is small. To avoid this, in this paper the criterion of [18] for a coefficient of P = 2 was used to generate continuous smooth surfaces. The results of the IDW interpolation were applied to the urban trace drawn using CorelDRAW X7 (Fig.…”

“…To accurately analyze T avg , an ST can be divided into positive trends (PT) and negative trends (NT); where a PT indicates an increase in T avg and an NT indicates a decrease [17][18]. For example, a PT of T avg indicates warming of a region and an NT indicates cooling.…”

“…For example, a PT of T avg indicates warming of a region and an NT indicates cooling. In northern Mexico, despite the existence of climate models on global and regional scales, which can be an important resource for decision makers taking action to counter the effects of climate change, this information is unrepresentative and therefore unsuitable for timely decision making [18]. Because of the lack of regional data on this important issue, the present study was designed to calculate seasonal estimates (June to September) of the magnitude of average annual trends of the following drought indicators: T avg , Prec, PET, SPEI-24, and return periods (RP) of drought (SPEI-24).…”